Introduction

Femara (chemical name: letrozole) is an aromatase inhibitor used to treat all stages of hormone receptor-positive breast cancer in post-menopausal women.

Letrozole is a medicine used to treat breast cancer and help to prevent breast cancer from coming back. It's mainly prescribed for women who have been through menopause and have a type of cancer called hormone-dependent breast cancer. Most people who take letrozole will have had primary treatment such as surgery, radiotherapy, or sometimes chemotherapy to treat their breast cancer first. Letrozole is an additional (adjuvant) treatment that helps stop the cancer from coming back. Letrozole is sometimes given alongside another breast cancer medicine called tamoxifen. Letrozole is available on prescription only and comes as a tablet.

Mechanism of action

Femara works by blocking the enzyme aromatase, which turns the hormone androgen into small amounts of estrogen in the body. This means less estrogen is available to stimulate the growth of hormone receptor-positive breast cancer cells. Female hormones that occur naturally in the body can increase the growth of some breast cancers. Letrozole works by decreasing the amounts of these hormones in the body. Femara will not work on hormone receptor-negative breast cancer.

In addition, regarding fertility, lowering estrogen levels can help the body release other hormones and chemicals to help immature eggs (known as follicles) grow and mature, increasing the likelihood of pregnancy.

Side effects

Like almost all breast cancer medicines, Femara can cause side effects, some of them severe.

The most common side effects of Femara are:

hot flashes

joint and bone pain

flushing

weakness

swelling

headache

dizziness

high cholesterol

excess sweating

Other serious side effects of Femara may include:

Bone loss: Because Femara lowers the amount of estrogen in the body, less estrogen reaches bone cells, leading to bone thinning and weakening, and a higher-than-average risk of breaking a bone. If you've been diagnosed with osteopenia or osteoporosis, your doctor will likely monitor your bone density while taking Femara.

High cholesterol: In some cases, Femara can increase your blood cholesterol levels. If you have high cholesterol, your doctor will likely monitor your cholesterol levels while taking Femara.

Dizziness and fatigue: Because Femara can make you feel extremely tired or dizzy, you should be careful when driving or using machinery until you know how Femara affects you.

Research suggests that up to half of the women prescribed Femara or another hormonal therapy medicine stop taking the medicine early, in many cases because of troubling or painful side effects. Still, it's essential to know that taking hormonal therapy for the prescribed amount of time can reduce the risk of recurrence by 50% and can reduce the risk of dying from breast cancer by about 30%.